Hermetic motor-compressor unit



March23i 4 K. M. GERTEIS HERMETIC MdToR-coMPREssoR UNIT Filed Nov. 14. 1950 mm mm I l ii INVEN TOR.

Patented Mar. 23, 1954 HEBMETIC MOTOR-COMPRESSOR UNIT Karl M. Gerteis, Syracuse, N. Y., assignor to Carrier Corporation, Syracuse, N. Y., a corporation of Delaware Application November 14, 1950, Serial N 0. 195,548

6 Claims.

This invention relates to a hermetic motorcompressor unit and, more particularly, to a hermetic motor-compressor unit in which loss of oil from the crankcase at start-up i minimized and minimum oil circulation through the refrigerant system during operation is attained.

In reciprocating compressors employing dichlordifluoromethane or other refrigerants miscible with lubricating oil as a refrigerant, frequently, at start-up excessive loss of oil from the crankcase occurs due to foaming so that insufficient lubricant is available during operation of the compressor. Under such circumstances, the lubricant is carried from the compressor by the refrigerant so that not only is insuificient lubricant available but the efiiciency of heat exchange of the refrigeration system is greatly reduced. These disadvantages are particularly serious in hermetic motor-compressor units in which the motor is cooled by suction gas of the refrigeration system.

The chief object of the present invention is to provide a hermetic motor-compressor unit in which such disadvantages are eliminated or greatly reduced.

An object is to provide a hermetic motorcompressor unit in which serious loss of lubricant from the crankcase at start-up is prevented.

A further object is to provide a hermetic motorcompressor unit including means to separate lubricant from refrigerant and to return the lubricant to the crankcase of the unit. Other objects of my invention will be readily perceived from the following description. I

This invention relates to a hermetic motorcompressor unit which includes in combination a crankcase. a motor compartment, a partition separating the crankcas and the motor compartment, a shaft extending from the crankcase compartment into the motor compartment, the shaft being connected to the rotor of the motor and to the pistons of the compressor, and means on the shaft to reduce pressure in the crankcase below the pressure in the motor compartment. A check valve is placed in the partition to permit return of lubricant from the motor compartment to the crankcase when pressure in the motor compartment opens the valve.

The attached drawing illustrates a preferred embodiment of my invention, in which Figure 1 is a plan view of the hermetic motorcompressor unit of the present invention;

Figure 2 is a sectional view taken on line II-II of Figure 1; and

Figure 3 is a view artly in elevation and partly in section taken on line III- 1H of Figure 1.

Referring to the attached drawing, there is shown the hermetic motor-compressor unit of the present invention. The compressor section 2 includes a crankcase 3 having a filter screen 4 therein, cylinders ii and cylinder heads 6. The pistons i of the compressor are connected by eccentric straps 8 to an eccentric shaft 9 which passes through crankcase 3 into the motor compartment it and is rotated by the motor I I since the rotor l2 of the motor H is mounted thereon.

Suction gas enters the manifold [3 as shown at Hi and is directed by baffle l5 over motor I l to cool the same, leavin motor compartment [0 through a port (not shown) to pass to the cylinder heads 6 where it is drawn into the compression chamber formed by cylinder 5 and compressed, the compressed gas passing through discharge valve it to the condenser (not shown) of the refrigeration system. Pressure in the motor compartment during operation is suction pressure.

A pump H is provided to draw lubricant from the sump of crankcase 3 through line l8 and to distribute the lubricant to the bearings, etc., of the unit, the distributed lubricant returning to the crankcase in the usual manner. Reciprocating compressors are well-known in the industry and hence do not require detailed description.

crankcase 3 and motor compartment I!) are separated by a partition is containin an opening as connecting the lower portion of compartment it and the sump of the crankcase 3. Openin 2b is closed by a check valve 2| placed on the crankcase side of the portion.

An opening 22 extends longitudinally through shaft 9 from the motor end 23 and terminates in that portion of the shaft extending within crankcase 3. A second opening 24 extends laterally through the shaft and connects opening 22 with the interior of the crankcase. A hollow tube 25 is connected to shaft 0 at end 23, the opening therein being connected to the longitudinally extending opening 22. Tube 25 includes a portion 26 extending axially of shaft 9 and a second portion 2? extending at an angle to shaft 3. Tube 25 is so mounted on shaft 9 that it rotates therewith. Tube 25 rotates at motor speed and in efiect serves as a centrifugal pump, developing sufficient head and capacity to pump the gas leaking from the cylinder between the cylinder and the piston and piston rings from the crankcase to the motor compartment and also maintains a lower pressure in the crankcase than exists in the motor compartment. Maintenance of such lower pressure in the crankcase permits oil to return from compartment l0 to the crankcase through opening 20 and check valve 2 l.

At start-up, if some minor amount of foam escapes through tube 25, it need pass through motor rotor 12 and two large spaces before it reaches the suction valves of the cylinders. The rotor and these spaces serve effectively as oil separators thereby further reducing loss of oil from the crankcase and the possibility of slugirls.

The opening 24 in that portion of shaft 9 extending in crankcase 3 acts as a centrifuge to limit loss of oil from the crankcase when foaming occurs at start-up. The present invention permits a high oil level to be maintained in the crankcase thereby effecting great savings in size, weight, and cost of the compressor.

The reduction in crankcase pressure results from the centrifugal head developed by spinning tube 25 and is relatively constant at all suction pressures.

While I have described a preferred embodiment of my invention, it will be understood my invention is not limited thereto since it may be otherwise embodied within the scope of the fo1- lowing claims.

I claim:

1. In a hermetic motor-compressor unit in which the motor has a rotor and the compressor has pistons, the combination of a crankcase compartment, a motor compartment through which suction gas passes to the compressor, a partition separating the compartments, a shaft extending from the crankcase compartment into the motor compartment, said shaft being connected to the rotor of the motor and to the pistons of the compressor, a check valve in the partition, and means in said shaft to reduce pressure in the crankcase compartment below the pressure in the motor compartment to permit lubricant to return to the crankcase compartment from the motor compartment through the check valve.

2. In a hermetic motor-compressor unit in which the motor has a rotor and the compressor haspistons, the combination of a crankcasecompartment, a motor compartment, a partition separating said compartments, a shaft extending from the crankcase compartment into the motor compartment, said shaft being connected to the rotor of the motor and to the pistons of the compressor, means in the partition to permit lubricant collected in the motor compartment to return to the crankcase compartment, and a pump means mounted on the shaft in the motor compartment and connected to the crankcase compart'ment to exhaust refrigerant gas therefrom.

3. A hermetic motor-compressor unit according to claim 2 in which said shaft has a passageway extending longitudinally therethrough, the pump means being connected to the crankcase compartment by said passageway, and said shaft having a second passageway connected to said first passageway at an angle to provide an inlet in the crankcase compartment.

4. In a hermetic motor-compressor unit in which the motor has a rotor and the compressor has pistons, the combination of a crankcase shaft, a crankcase compartment, a motor compartment, a partition separating said compartments, a shaft extending from the crankcase compartment into the motor compartment, said shaft being connected to the rotor of the motor and to the pistons of the compressor, means in the partition to permit lubricant collected in the motor compartment to return to the crankcase compartment, a pump member mounted on the shaft in the motor compartment, said shaft having a passageway extending longitudinally therethrough, said pump member being connected to the crankcase compartment by said passageway, and said shaft having a second passageway connected to said first passageway at an angle to provide an inlet in the crankcase compartment, said pump member comprising a hollow tube having a portion extending axially of the shaft and a second portion extending at an angle to the axis of the shaft, said tube being mounted on the end of the shaft and rotating therewith.

5. A hermetic motor-compressor unit according to claim 4 in which the lubricant return means include an opening in the partition and a. check valve closing said opening to permit the return of lubricant from the motor compartment to the crankcase compartment when pressure in the motor compartment opens said check valve.

6. A hermetic motor-compressor unit according to claim 5 in which the inlet of the second passageway serves as a centrifuge to separate lubricant from refrigerant gas in foam created at start-up of the device.

KARL'lVI. GER'I'EIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,945,338 Terry Jan. 30, 1934 2,085,356 Greenwald June 29, 1937 2,100,799 Drysdale Nov. 30, 1937 2,178,811 Sateren Nov. 7, 1939 2,228,364 Philipp Jan. 14, 1941 2,283,025 Wolfert May 12, 1942 2,298,749 Buschmann Oct. 13, 1942 

